U.S. Pat. No. 4,034,990, assigned to the assignee of the present application, relates to a technique for allowing interaction between symbols from signals recorded on a video medium (such as a video tape or disc) and regenerated by a video playback unit and symbols from a video game unit whereby the symbols from the video playback unit and the game unit are both dislayed on the screen of a cathode ray tube (CRT) display. The signals derived from the video playback unit are of such characteristic that data can be generated from them to identify, for example, where on the screen of the CRT the symbols from the video playback unit are, and, thus, permit the symbols from the game unit to interact with the symbols from the video playback unit.
In one embodiment described in the aforementioned patent, the video signals from the video playback unit which generate the symbols on the CRT display are coded by being generated at a maximum white level and decoded in the game unit by identifying signals of such maximum white level. The decoded signals can then be used to develop logic level signals which are time related to the symbol locations on the CRT screen and, thus, the logic signals can be used to indicate such things as coincidence between a signal generated from the video playback unit and signals generated by the game unit.
While this technique is adequate for many applications, it does have its drawbacks. The amount of data which can be encoded by such level identification is small.
Accordingly, it is an object of this invention to provide an improved interactive video playback unit system.